The periodic table is a masterpiece of organized chemical information. It is a table of the chemical elements in which the elements are arranged by order of atomic number. The standard form of the table includes periods (horizontal rows in the periodic table) and groups (vertical rows in the periodic table). Atoms are the basic building blocks of ordinary matter. Atoms are made up of particles called protons, electrons, and neutrons. Protons carry a positive electrical charge, electrons carry a negative electrical charge, and neutrons carry no electrical charge at all. The protons and neutrons come together in the central part of the atom, called the nucleus, and the electrons ‘orbit’ the nucleus in the electron cloud. An element is a substance that is made entirely from one type of atom.
For example, the element hydrogen is made from atoms containing a single proton and a single electron. If you change the number of protons an atom has, you change the type of element it is. There are 117 different elements. According to the atomic model, electrons orbit the nucleus at specific levels, or shells. Electrons fill shells, starting from the innermost, going to the outermost. Electrons in the outermost shell, which are involved in bonding, are known as valence electrons. When many types of atoms come into contact with one another, electrons can be transferred from one atom to another thus creating an ion. An ion is an atom that has lost or gained an electron. Ions form because neutral atoms become charged by the losing or gaining an electron. An anion is created when one atom gains electrons.
On the contrary, a cation is created when an atom loses electrons. The octet rule is a simple chemical rule that states that atoms tend to attract each other in such a way so that they each have eight electrons in their valence shells. The octet rule is applicable to the main-group elements, especially carbon, nitrogen, oxygen, and the halogens (five nonmetal elements found in group 17 of the periodic table), but also the metals in the first two columns of the periodic table.
In simple terms, the octet rule says that atoms are more stable when their outer shell is filled, and therefore, atoms will lose, gain, or share electrons to completely fill their outer shells. An Ionic compound is a bond between a positively charge molecules (cations) with a negatively charged molecules (anions). Ionic compounds are formed between a metal and a non-metal. The metal loses the valence electrons to the non-metal thus forming ionic bonds due to the attraction between the cations and the anions.